In recent years, increase in size of liquid crystal display devices requires increase in size of color filters for use in the liquid crystal display devices. In a process of producing a color filter, patterning is performed by using a photolithography method to form colored layers and black matrixes. In a one-shot exposure method using a real-size exposure mask, a large exposure mask needs to be used. Since such a large exposure mask is very expensive, a problem arises that production cost for the color filters may be increased.
In order to solve this problem, a method (hereinafter, referred to as a “small mask continuous exposure method”) may be used in which an exposure device having a plurality of exposure heads mounted thereto is used, and a small exposure mask is mounted to each exposure head, and exposure to light is repeatedly performed for a substrate that is a subject to be exposed to light such that the entire surface of the substrate is exposed to light.
FIG. 7 is a diagram illustrating an arrangement of exposure masks in the small mask continuous exposure method.
Exposure masks 18 are mounted to a plurality of exposure heads, respectively, and are aligned in two rows in the X-axis direction. The exposure masks 18 mounted to exposure heads in one of the rows are arranged so as to complement spaces between the exposure masks 18 by using the exposure masks 18 mounted to corresponding adjacent exposure heads in the other of the rows, so that pitches between the mask patterns formed on a photomask become uniform without generating any space.
More specifically, spaces are provided between the exposure masks in each row, and patterning for the spaces in one of the rows is performed through baking so as to be mutually complemented by masks aligned in the other of the rows. For example, in the drawings, a portion between a portion exposed to light by using the exposure mask 18 positioned at a position P1 and a portion exposed to light by using the exposure mask 18 positioned at a position P2 is exposed to light by using the exposure mask 18 positioned at a position P3. Thus, end portions of each exposure pattern in the X-axis direction are joined to each other (hereinafter, a portion at which the exposure patterns are joined to each other is referred to as a “joining portion”).